Collagen is the major component of extracellular matrix. Collagen cross-link and deposition depend on lysyl hydroxylation, which is catalyzed by procollagen-lysine, 2-oxoglutarate 5-dioxygenase (PLOD). Aberrant lysyl hydroxylation and collagen cross-link contributes to the progression of many collagen-related diseases, such as fibrosis and cancer. Three lysyl hydroxylases (LH1, LH2, and LH3) are identified, encoded by PLOD1, PLOD2, and PLOD3 genes. Expression of PLODs is regulated by multiple cytokines, transcription factors and microRNAs. Dysregulation of PLODs promotes cancer progression and metastasis, suggesting that targeting PLODs is potential strategy for cancer treatment. Here, we summarize the recent progress in the investigation of function and regulation of PLODs in normal tissue development and disease progression, especially in cancer.

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Myeloid-derived suppressor cells (MDSC) have been identified as a population of immature myeloid cells that suppress anti-tumor immunity. MDSC are increased in tumor-bearing hosts; thus, depletion of MDSC may enhance anti-tumor immunity. Histone deacetylase inhibitors (HDACi) are chemical agents that are primarily used against hematologic malignancies. The ability of these agents to modulate anticancer immunity has recently been extensively studied. However, the effect of HDACi on MDSC has remained largely unexplored. In the present study, we provide the first demonstration that HDACi treatment decreases MDSC accumulation in the spleen, blood and tumor bed but increases the proportion of T cells (particularly the frequency of IFN-γ- or perforin-producing CD8 T cells) in BALB/C mice with 4T1 mammary tumors. In addition, HDACi exposure of bone marrow (BM) cells significantly eliminated the MDSC population induced by GM-CSF or the tumor burden in vitro, which was further demonstrated as functionally important to relieve the inhibitory effect of MDSC-enriched BM cells on T cell proliferation. Mechanistically, HDACi increased the apoptosis of Gr-1 cells (almost MDSC) compared with that of Gr-1 cells, which was abrogated by the ROS scavenger N-acetylcysteine, suggesting that the HDACi-induced increase in MDSC apoptosis due to increased intracellular ROS might partially account for the observed depletion of MDSC. These findings suggest that the elimination of MDSC using an HDACi may contribute to the overall anti-tumor properties of these agents, highlighting a novel property of HDACi as potent MDSC-targeting agents, which may be used to enhance the efficacy of immunotherapeutic regimens.

PurposeCancer-associated fibroblasts (CAFs) activated by cancer cells has a central role in development and malignant biological behavior in colorectal cancer (CRC). Adult fibroblasts do not express Snail, but Snail-positive fibroblasts are discovered in the stroma of malignant CRC and reported to be the key role to chemoresistance. However, the reciprocal effect of CAFs expressed Snail to chemoresistance on CRC cells and the underlying molecular mechanisms are not fully characterized.Materials and MethodsSnail-overexpressed 3T3 stable cell lines were generated by lipidosome and CT26 mixed with 3T3-Snail subcutaneous transplanted CRC models were established by subcutaneous injection. Cell Counting Kit-8, flow cytometry and western blotting assays were performed, and immunohistochemistry staining was studied. The cytokines participated in chemoresistance was validated with reverse transcriptase-polymerase chain reaction and heatmap.ResultsSnail-expression fibroblasts are discovered in human and mouse spontaneous CRCs. Overexpression of Snail induces 3T3 fibroblasts transdifferentiation to CAFs. CT26 co-cultured with 3T3-Snail resisted the impairment from 5-fluorouracil and paclitaxel in vitro. The subcutaneous transplanted tumor models included 3T3-Snail cells develop without restrictions even after treating with 5-fluorouracil or paclitaxel. Moreover, these chemoresistant processes may be mediated by CCL1 secreted by Snail-expression fibroblasts via transforming growth factor β/nuclear factor-κB signaling pathways.ConclusionTaken together, Snail-expressing 3T3 fibroblasts display CAFs properties that support 5-fluorouracil and paclitaxel chemoresistance in CRC via participation of CCL1 and suggest that inhibition of the Snail-expression fibroblasts in tumor may be a useful strategy to limit chemoresistance.

BackgroundIncreased collagen expression and deposition are associated with cancer progression and poor prognosis in breast cancer patients. However, function and regulation of membrane-associated collagen in breast cancer have not been determined. Collagen XIII is a type II transmembrane protein within the collagen superfamily. Experiments in tissue culture and knockout mouse models show that collagen XIII is involved in cell adhesion and differentiation of certain cell types. In the present study, we determined roles of collagen XIII in breast cancer progression and metastasis.MethodsWe analyzed the association of collagen XIII expression with breast cancer development and metastasis using published gene expression profiles generated from human breast cancer tissues. Utilizing gain- and loss- of function approaches and 3D culture assays, we investigated roles of collagen XIII in regulating invasive tumor growth. Using the tumorsphere/mammosphere formation assay and the detachment cell culture assay, we determined whether collagen XIII enhances cancer cell stemness and induces anoikis resistance. We also inhibited collagen XIII signaling with β1 integrin function-blocking antibody. Finally, using the lung colonization assay and the orthotopic mammary tumor model, we investigated roles of collagen XIII in regulating breast cancer colonization and metastasis. Cox proportional hazard (log-rank) test, two-sided Student’s t-test (two groups) and one-way ANOVA (three or more groups) analyses were used in this study.ResultsCollagen XIII expression is significantly higher in human breast cancer tissue compared with normal mammary gland. Increased collagen XIII mRNA levels in breast cancer tissue correlated with short distant recurrence free survival. We showed that collagen XIII expression promoted invasive tumor growth in 3D culture, enhanced cancer cell stemness, and induced anoikis resistance. Collagen XIII expression induced β1 integrin activation. Blocking β1 integrin activation significantly reduced collagen XIII-induced invasion and mammosphere formation. Importantly, silencing collagen XIII in MDA-MB-231 cells reduced lung colonization and metastasis.ConclusionsOur results demonstrate a novel function of collagen XIII in promoting cancer metastasis, cell invasion, and anoikis resistance.Electronic supplementary materialThe online version of this article (10.1186/s13058-018-1030-y) contains supplementary material, which is available to authorized users.